This invention relates to an improved hydrometallurgical process for obtaining copper from a copper sulfide ore. This invention particularly relates to a simple continuous process of leaching copper from a copper sulfide with a cupric chloride lixiviant.
Processes in which copper is leached from a copper sulfide with a cupric chloride lixiviant have been known for a long time. See, for example, U.S. Pat. Nos. 507,130, 552,960, 1,263,727, 3,692,647, 3,776,826, 3,785,944, and 4,013,457.
However, such hydrometallurgical processes have tended to be significantly more expensive than conventional pyrometallurgical processes for making copper. As a result, it has only been since the advent of increasingly stringent air pollution control regulations and standards, promulgated by Federal and State agencies within the last few years, that such hydrometallurgical processes have appeared attractive. Such hydrometallurgical processes do not produce the toxic and noxious emissions of suspended particulate materials and sulfur oxides which can be a problem with conventional pyrometallurgical processes. In this regard, the particularly troublesome sulfur oxides, produced by conventional pyrometallurgical processes, are not produced by such hydrometallurgical processes which convert any sulfur compounds into solid elemental sulfur.
However, to be practical, a hydrometallurgical process for obtaining copper has had to provide for essentially complete recovery of all the copper in the copper sulfide. In addition, the use of moderate process temperatures and pressures has been preferred to avoid high capital and operating costs. Furthermore, the copper produced has had to be of a high grade, so that further expensive processing of the copper to obtain commercially acceptable anode copper can be minimized. In addition, regeneration of the reagents, used in the process, has been important to keep costs low. Finally, it has been important that little or no toxic wastes be produced by the process.